Light effect and light node editing

- Add a new plugin for CCLightNode.
- Add a new effect control for CCEffectLighing.
- Add the new TokenArray property type for serializing light group string arrays.
- Light icons in the stage are rendered in their own layer so they stay at the same scale when the scene is zoomed. Light icons take on the diffuse color of the lights they represent and there are different icons for the point and directional light types.